Section E: Optics

Question 1

What does Thin Lenses mean?

Answer 1

are lenses where the centre substances are negligible and the total power is equal to the sum of the surface powers

Question 2

What is a chief ray?

Answer 2

image always lies on it, passes through lens undeviated and passes through OC

Question 3

when does a chief ray occur

Answer 3

only in thin lenses

Question 4

how to find magnification

Answer 4

L/L’

Question 5

How to find image size

Answer 5

h’ = h x L/L’

Question 6

How to find position of lens

Answer 6

l’ = n / L’

Question 7

How to find power leaving the lens

Answer 7

L’ =L + F

Question 8

How to find power entering the lens

Answer 8

L= n/l

Question 9

What happens if:Mag is negative
Mag is smaller than 1
Mag is larger than 1

Answer 9

1. Negative = inverted
2. Smaller = image smaller than object
3. Bigger = image bigger than object

Question 10

when asked to describe the nature of the image

Answer 10

Position, orientation & englared or diminshed

Question 11

How to find image size with distant object?

Answer 11

Either use trig Or h’ =-f’x tan 0

Question 12

What happens with a distance object?

Answer 12

L and l = 0 and L’ = F